Internal combustion engine



Jan. 1, 1935. A. A. WlDMANN INTERNAL COMBUSTION ENGINE Filed NOV. 13,1931 firm fi. MDMHNN.

Patented Jan. 1, 1935 INTERNAL COMBUSTION a Adolf A. Widmann,.Detroit,Mich-., assignor "to Hermann I. A; Dorner,nDetroit,iMich-. a w

Application November 13, 1931, Sam noitxzfn aej 1' I,

' 2 Claims. (0141215494)" I if This invention relates to internal.combustion engines and more particularly to engine crank caseconstruction;

For many:- uses, it is becoming more and more 8" essential that enginesmust be light,.and in this connection crank case construction: is one ofthe. chief'considerations: The-choice of materials has been one-"of: thememe-factors. im determiningr;

withstand. the explosivepressures at the points. of:-

cylinder attachment, and" such wall thickness: even. with thematerialsrabove mentioned, result. in undesirable: weight in manyinstances and par ticularly: whenthe. engineis of a high. pressure.

' 28 is av compartmentifor.housingvalve actuating 20 type, suchasiDiesel engines. 7

light inweightandatthesametime-rugged; Another object. of the inventionis. to provideacrank case structure for; radial engines. in which 25 theinterior wallscarrying the crank. shaftcan be.

formed of relatively thin material.throug-hbeingv placed in compressionwhich cannot be overcome by forces; developed: duringvexplosionswhich-tend to move portions of the walls in; oppositedirec'-,

tions..;

other obiectsof. the iEVGDtiOIIzWillappear from: thefollowingdescription' taken, in connection withv theaccompan'yingg drawing;vforming a; part. of; thepanded around the crank case by adjustmentiofy'35 specificationgimwhich:

the crankcasestructure:imsection.

Fig. 2 is an end view of the same taken on line 22 of Fig. 1. p

Fig. 3 is another sectionalview of a fragment of the engine taken online 3-3 of Fig. 2.

Referring now to the drawing by the characters of reference, 10indicates generally a barrel type of crank case having the main portionthereof formed preferably as a casting or forging and of 4 material suchas aluminum or duralumin. The outer wall 11 of the crank case issubstantially circular in form except for flat faces 12 upon whichflanges 13 on the cylinders 14 seat. In order to secure the cylinders tothe crank case, 50 studs 15 are secured in the flat faces of the wall 11and project through openings in the flanges 13 and nuts 16 are screwedupon the studs to clamp the cylinder flanges'tightly against the flatfaces of the crank case. 55 A pair of reinforcing walls 17 and. 8 arepro- An obiect of: the invention is lJOZ PIOYiQG a. crank: casestructure for radial engines which'is.

Fig. 1 illustrates'a" radial Diesel enginehaving:

vided within. thecrank case and extend transversely ofthe interior.thereof forming, the chamber 1'9into-which-the cylinders extend. Thewall; 18is preferably formed integrally with the-peripheral wall 11,andzextending therefromis' a bearing 5 portion 20- in. whichoneendof-the crankshaft 2-1 is supported. The wall; 17 iszdetachably securedbybolts 23 to interior, crank case-bosses 22,-,and; this detachablereinforcing wall; carries a bearing: 24. which also supports thecrankshaft. 10

The crankshaft is, preferably formed 'in' tw parts, oneysection beingdetachably secured upon the crankipin 25 by a:clampmeans:26.jEncircl-ing. the crank pin is a masterrod hub 27' to. which: connectingrods iaarepivotallysecureds ina man.- 15 ner conventional with: radialtype. engines. End wall 28 isfdetachably secured to: the open rear'endiof; the: crankicaseyand. between the wallscl'l and" mechanism(nots'hown);

Imorderthat the-crank casewalls 17: 211(1'13'. can'be formedrelativelythin,.iso that: engine weight is, thereby. considerablyreduced;. I1 pro-* vide tension means fass'ociated with? the crank. casefor placing them in high compression. Such 25 tension. means consists ofa. plurality of: band segments onse'ctions; 58 which are connectedtogether at their adjacent ends by tensionz means 29. jAs shown,v theband segments are, provided with Y upturned. ends j 30 through whichthe; ten sion means, inthe form of a. bolt and:nut,,'isas sociated andtheadjacent .ends of band sections; are spaced so that they can becontracted or eXrithe nuts on thebolts. The crank caseisipreferably';

formed with two grooves extendingitherearound and in parallel relationin which the band means are seated. It is preferable that the band meansbe associated on opposite sides of the cylinders and in alignment withthe walls 17 and 18 so that the crank case compressing means is closelyadjacent the cylinder flanges. It will be noted that the'band meanssections are located'directly and entirely in engagement with thecrankcase and that the cylinders can be attached to or removed from thecrank case while the band means are secured around the crank case.

The band segments are connected to form two crank case encircling hoopswhich are in tension greater than that to which the crank case issubjected through any explosion force in the cylinders through theattaching means. It is also worthy of consideration in this connectionto note that a casting is much stronger when placed in compression andsubjected to tensile stresses than it is without compression, and withthe band means encircling and engaging the crank case in tension asabove set forth, there will be less tensile stress in the walls 1'? and18 resulting from explosion in the cylinders even though the cylindersare secured directly to the crank case by bolts or studs than if thebands were not used.

The band means herein described being directly in engagementwith thecrank case will distribute stresses around the crank case and thusrelieve the same of severe localized stresses which ordinarily resultfrom a bolted connection of this character, and therefore the thicknessof the walls 17 and 18 can be materially reduced relative to thatrequired in a crank case which is not under compression and'in whichonly bolt means are utilized to fasten the cylinders.

Assuming that there is an explosion occurring in the'top cylinder, asviewed in Figs. 1 and 2, the forces act against the cylinder tending tomove it upwardly and they act against the piston tending to move itdownwardly. As the cylinder is attached to the crank case, the upwardforces are transmitted to the portions of the walls 17 and 18 ad" jacentthe cylinder. As the piston is connected to the crank shaft which ismounted in bearings in the walls'l'l and'l8, the downward forces aretransmitted from the piston to the portions of the walls belowthe'bearings. Thus there are two sets of forces acting in oppositedirections on the walls 17 and 18 during explosion periods, such forcestending to move portions of each wall in opposite directions. One methodof providing sufllcient strength in the walls to withstand theseoppositely acting" forces is to make them thick but this methodintroduces weight which is undesirable where lightness is a factor suchas H it is in aeroplaneengines. By the employment of the tension bandmeans, asherein described, the walls 17 and 18 are compressed to anextent such that the oppositely acting 'forces cannot introduce stressesand thus relatively thin walls can be employed; The combined weight ofthe thin walls 1'7 and 18 and the'compressionband means has been foundto be less than that of walls of the thickness required when nocompression band means is employed.

Although the invention has been described in :walls being notsubstantially greater than the diameter of thecylinders, separate meansassociated with each cylinder for securing the same totheperipheral wallof the crank case for removal therefrom independently of the othercylinders, and a pair of tension devices independe'nt'of said'securingmeans and surrounding the peripheral wall of the crank case on eitherside of and adjacent the row of cylinders and substantially in line withthe said trans'verse'walls', said tension devices being under an initialtension" sufiicient to compress said transverse Walls to such an extentthat stresses transmitted to the latter by explosions in the v cylindersmay be adequately resisted-r 1 2. man internal combustion engine of theradial type, the combination with a crank case of barrel'form having aperipheral wall and relatively thin transverse walls, a crankshafthaving bearings in said walls, a plurality ofcylinder's mounted on theperipheral wall of the crankcase and disposed in a singlecircmnferential rowthereon closely adjacent to and intermediate saidtransverse walls, said transverse walls being spaced to an extentsuflicient to accommodate: the working parts of one circumferential rowonly of cylinders, the spacing between the transverse walls being notsubstantially greater than the diameter of the cylinders, means securingeach cylinder to the peripheral wallbfthe crankcase for independentremoval therefrom, a pair of tension devices independent of saidsecuring means and surrounding and directly engaging the peripheral wallof the crankcase oneither'side' ofand adjacent the row of cylinders andsub stantiallyjin line with the said transverse walls; said tension*devices being under an initial ten sion'sufficient to compress saidtransverse walls to such an extent that stresses transmitted to thelatter by explosions in the cylinders may be adequately resisted, meansfor preventing displacement'of said devices axially of thecrank case,pistons in the cylinders, and connecting rods between the pistons andcrankshaft.

. ADOLF'A. WIDMANN.'

